EARLY FORMS OF MICROTUBULE-ASSOCIATED PROTEIN ARE STRONGLY EXPRESSED IN CORTICAL DYSPLASIA

We report the enhanced expression of early forms of microtubule-associ ated proteins (MAPs) in cortical dysplasia in surgical resections from 17 children with intractable epilepsy. Large neurons, which represent one of the characteristic cellular features of cortical dysplasia, sh owed strong immunoreactivity for MAP1B, as well as the low-molecular-w eight isoform of MAP2 (MAP2c). In situ hybridization with MAP1B antise nse riboprobe showed markedly increased hybridization signal intensiti es in the large neurons, whereas neurons in the normal-appearing corte x and most of the normal-sized neurons in the dysplastic cortex had fa int signals. Because MAP2c and MAP1B are early forms of MAPs, which ar e abundantly expressed in the developing-brain and down-regulated in t he adult, and are thought to be involved in neuronal outgrowth and pla sticity, our results suggest that the structural remodeling of neurona l processes is activated in cortical dysplasia.